An asymmetric beauty factory operates at the (4 1 S 3 ), namely at s = 10580

An asymmetric beauty factory operates at the ϒ(4¹S₃), namely at √s = 10580 MeV, to study the process e⁺e^- → B⁰B̅⁰. ‘Asymmetric’ means that the centre of mass moves in the reference frame of the collider. Consider an event in which both mesons are produced with the Lorentz factor βγ = 0.56. The decay vertex of one of them is at 120 μm from the principal vertex; amongst the B decay products there is a μ⁺. How many lifetimes did the particle live? What can we say about the two flavours? The second B decays at 0.5 mm, again with a μ in its final state. How many lifetimes did it live? Can the μ be positive? Why?